Phenotypic alteration in malignant transformation of colonic villous tumours: with special reference to a comparison with tubular tumours.

Abstract

To clarify the cellular differentiation of colorectal villous tumours in malignant transformation, compared with that of tubular tumours (tubular adenoma and adenocarcinoma arising in tubular adenoma). Forty-nine cases of colorectal villous tumours [six cases of low-grade villous adenoma, 21 of high-grade villous adenoma (VA), nine of invasive carcinoma in villous adenoma (CIVA), and 13 of pure villous carcinoma (PVC)] and 46 cases of tubular tumours [14 cases of low-grade and 17 of high-grade tubular adenoma (TA), and 15 cases of carcinoma in tubular adenoma (CITA)] were selected for this study based on their expression patterns of CD10 (small intestinal brush border), MUC2 (intestinal goblet cell), and HGM (gastric foveolar epithelium). HGM was more frequently expressed in the adenomatous components of villous tumours (63%) than in those of tubular tumours (14%) (P < 0.05). CD10 expression of high-grade TAs (47%) and carcinomas arising in TA (60%) was significantly higher than that of villous tumours (0%) (P < 0.05). There were significant differences in the phenotypic expression of adenoma and adenocarcinoma between villous and tubular tumours, respectively. Villous tumours have a pathway of malignant transformation different from that of tubular tumours. Because of biological differences, colorectal villous tumours should be distinguished from tubular neoplasia. The analysis of the phenotype of colorectal neoplasms is useful for the evaluation of tumour progression.